(a) Field of the Invention:
The present invention relates to a dental diagnosing device, and more particuraly, to a detector for diagnosing dental caries able to indicate the presence and progress of the dental caries with a plurality of indicating lamps classified, for example, by converting them into an electric parameter such as an electric resistance.
(b) Description of the Prior Art:
Lengthy study has shown that presence of the initial dental caries and the progress of dental caries can be diagnosed by measuring the electrical resistance between the teeth and buccal mucous membrane. Specifically, it has been shown that caries do not exist or the probability of occurrence of the caries is small when the electrical resistance shows a value more than 600.OMEGA., or when a coloring, chalk-like variation or the like is observed on the top surface of the teeth. It is necessary to observe adequately the subsequent changes when the electrical resistance takes a value between 599.about.251k.OMEGA. and the progress of the caries has arrived in the region of the dentine of the teeth, because it will become the dentine caries after 1 or 2 years almost without exception when the electrical resistance takes a value between 250.about.15.1k.OMEGA., regardless of the appearance of the teeth. In addition, the exposure of the pulp is apparently indicated when the electrical resistance takes a value less than 12k.OMEGA., but treatment for restoring the pulp is usually judged clinically proper when the electrical resistance takes a value of less than 18k.OMEGA..
Based upon the results of the study mentioned above, a device for diagnosing dental caries was disclosed in Japanese Patent Publication No. 46-12400 published Mar. 30, 1977 and is in practical use. The conventional device of this sort is formed with a measuring and indicating device portion comprising a tooth electrode, power switch and plurality of indicating lamps and, a measuring circuit device portion being independent of the measuring and indicating device portion and comprising a reference voltage adjusting circuit, low frequency oscillating circuit, amplifying circuit, voltage comparing circuit, and the. However, because it is used by connecting these two device portions with a cord, such problems as a disconnection of the cord, an imperfection of the connection, and the like might occur. Moreover, the conventional device is provided with only an indicating lamp which lights when the teeth resistance is more than 600k.OMEGA., an indicating lamp which lights when the teeth resistance is between 600k.OMEGA..about.250k.OMEGA., and an indicating lamp which lights when the teeth resistance is less than 250k.OMEGA.; thus, a user is not able to judge with these indicating lamps whether the amputation of dental pulp is necessary.